The objective of this pilot study is provide data for planning and to establish the feasibility of performing a large, randomized, comparative effectiveness trial of two specially designed airway tubes (endotracheal tubes; ETTs) for the prevention of ventilator-associated pneumonia (VAP). Modification of the material and design of the ETT cuff that is positioned in the trachea, and/or continuous aspiration of subglottic secretions through an extra port positioned between the tube cuff and the vocal chords may prevent leakage of contaminated secretions around the cuff and thereby reduce the risk of VAP. The investigators are planning a phase III, randomized, controlled trial comparing the effectiveness of a polyurethane-cuffed endotracheal tube (PUC-ETT), a polyurethane-cuffed tube that also allows continuous aspiration of subglottic secretions (PUC-CASS-ETT), and a conventional, polyvinylchloride-cuffed endotracheal tube (PVC-ETT) in mechanically ventilated patients with respiratory failure. Prior to initiating the Phase III trial, a smaller pilot study is necessary in order to establish feasibility and to gather data on endpoints in order to establish enrollment rates and project sample size for the definitive trial. For the purposes of planning, a surrogate for VAP, bacterial colonization of the trachea will be assessed from daily quantitative cultures to allow estimation of effect size for the two study devices. VAP will be diagnosed using objective criteria, based on cultures from bronchoalveolar lavage. The safety profile of the tubes will be evaluated using a multi-faceted approach, including short-term objective measures of laryngeal dysfunction and long-term subjective and objective assessment of upper airway problems via phone interview post-hospital discharge, and recording of device-related adverse events.